1. Field of the Invention
The invention is concerned with using zirconium and/or hafnium sponge metal fines and similar fines of other exotic metals, such as titanium and uranium, to economic advantage.
2. Description of the Prior Art
Zirconium and/or hafnium metal values are customarily placed in socalled "sponge" condition as part of the production of pure zirconium and/or hafnium metal from zircon sand. An impure regulus of zirconium and/or hafnium sponge metal containing some magnesium and magnesium chloride is produced by reducing zirconium and/or hafnium tetrachloride powder with magnesium and by heating the resulting mixture of zirconium and/or hafnium and magnesium and magnesium chloride in a vacuum distillation retort to distill off most of the magnesium and magnesium chloride with other volatile impurities. The regulus of zirconium and/or hafnium sponge is crushed to break it into size suitable as feed to a melting step in the production of an ingot of useable zirconium and/or hafnium metal.
About five to ten percent by weight of unusable and highly pyrophoric fines (e.g. minus twenty mesh standard Tyler screen) are produced during crushing. The only known way to utilize these fines is to burn them into zirconium and/or hafnium oxide and add the oxide to zircon sand in a chlorination step of the overall process. However, by this practice, the value of the sponge constituting the fines is essentially lost.